Hitherto, as a technique for specifying a region of a photographic subject in an image, the technique called visual attention has been known (for example, see Non Patent Literature 1).
In visual attention, luminance information, color information, and edge information are extracted from an input image that has been input, and information maps obtained based on these extracted items of information are added to generate one Saliency Map (hereinafter referred to as a photographic subject map).
This photographic subject map is information that indicates the likeliness of each region of the input image being a region of a photographic subject. That is, the pixel value of a pixel of the photographic subject map indicates the likeliness of a pixel (region) of the input image that is at the same position as that pixel being a region of a photographic subject. Therefore, in which region of the input image a photographic subject is included can be specified by using the photographic subject map.